THX.OK,original Qs are about permutatios.The paper is not very u

来源: jinjing 于 2012-04-16 10:36:55 [旧帖] [给我悄悄话] 本文已被阅读：次

For n,

i*j 表i个j头. P(i1*j1,i2*j2,...,is*js)=C(n,i1)C(n-i1,i2)...C(n-i1-i2...i(s-1),is)*n!/(j1!j2!...js!)*.9 . Sigma (i1j1+...+isjs=10).P(i1j1...,isjs)=900...00.

(n-1)个0.